guitar pro - reading slap

on some of the tablature written for slap bass for guitar pro bass lines they have a notation "X" which i think indicates muted note but im not sure what it means cause there is an S on top these notes which indicated slap. I dont know how to read slap tablature.

Often you will find with GP files, people won't include those S and Ps, they leave that open to interpretation. The "S" can be slap, but sometimes your technique will tell you to do otherwise (ex. Sometimes I'll strum where it says slap). So yes, S over the x is slap a dead (muted) note.